dallara F305 - Front Castor Angle Setting; Rear Castor Angle Setting

FRONT CASTOR ANGLE SETTING 8
When the car is flat (same ride height front and rear), the upright inclination angle
(apparent castor) is 1.75° and the castor angle (build in castor) is 10.5°.
With different front and rear ride heights: For instance, with 15 mm front and 28mm rear
ride height, measured at wheel axis, (wheelbase is 2710 mm) you would measure a
‘apparent’ castor angle of 2.03°:
Pitch angle [(30-15)/2710] x 57.29 = 0.32°
‘Build in’ castor angle becomes: 10.5° - 0.32° = 10.2° (corresponding to a 2.07°
measured ‘apparent’ castor angle)
each change in front and/or rear ride height alters the castor angle
REAR
The rear wheel ‘castor’ angle can be measured to check bump steer to be zero. You can measure
the angle on the brake calliper mounting platforms.
When the car is flat (front ride height is equal to rear ride height) and you measure ‘apparent’ castor
of 23°, the ‘castor’ angle is 16° and bump steer is zero.
Castor on the rear axle is not relevant as the wheels are not steered.